When semiconductor parts and flat display panels are manufactured, various substrate processing steps are generally performed by a substrate processing system, for cleaning and drying front and rear surfaces of semiconductor wafers, liquid crystal substrates, and so on. The substrate processing systems are classified into a wafer-fed type substrate processing system that processes substrates one by one, and a batch type substrate processing system that collectively processes a plurality of substrates. Either one of the substrate processing systems is selected and used, depending on scales or kinds of process steps for semiconductor parts.
In particular, the batch type substrate processing system that collectively processes a plurality of substrates is used with a view to reducing a process time required for each substrate so as to improve a throughput of the process. In order thereto, a further improvement in throughput is desired in the batch type substrate processing system.
For this reason, the batch type substrate processing system can not only collectively process a plurality of substrates (e.g., twenty-five substrates) contained in one carrier, which is used for transferring the substrates from one process step to another process step, but also collectively process the larger number of substrates, for example, fifty substrates, contained in a plurality of carriers (two carriers, for example). In order to achieve this, a batch forming apparatus is used for forming a batch of, e.g., fifty substrates, by combining the substrates contained in a plurality of carriers, e.g., two carriers. In the batch type substrate processing system, the substrates forming such a batch can be collectively processed. To be specific, each batch of substrates is subjected to various substrate processing steps such as a cleaning step, a drying step, etc.
A conventional substrate processing system includes: a carrier loading/unloading part that loads/unloads a carrier in which a plurality of substrates are contained in a stacked manner; a batch forming part that forms a batch of substrates to be collectively processed, by combining the substrates contained in a plurality of carriers; and a substrate processing part that cleans and dries each batch of the substrates. The batch forming part includes: a substrate transfer mechanism capable of simultaneously transferring the substrates contained in one carrier; and a batch forming mechanism that forms a batch of substrates by combining the substrates transferred by the substrate transfer mechanism. In order to form a batch of substrates, the substrate transfer mechanism takes out a plurality of substrates from a first carrier and transfers the same to the batch forming mechanism in which the substrates are turned to be vertically aligned with small gaps therebetween.
Then, the substrate transfer mechanism takes out a plurality of substrates from a second carrier and transfers the same to the batch forming mechanism in which the substrates are turned to be vertically aligned, such that each of the substrates transferred from the second carriers is interposed between the substrates that have been transferred from the first carrier. Thus, a distance between the substrates of the batch of substrates formed by the batch forming mechanism is about one half a distance between the substrates which have been contained in the respective carriers. In this manner, a batch of fifty substrates is formed by the batch forming mechanism in the batch forming part (see, for example, JP2002-64075A).
In the above conventional substrate processing system, the plurality of substrates contained in the respective carriers are merely, sequentially transferred as they are from the carriers to the batch forming mechanism, without changing positional relationships of the substrates relative to each other. Thus, there may be a case in which a batch of substrates formed by the batch forming part lacks one or more substrates, because the substrates contained in the respective carriers fail to successively be aligned in a row with one or more substrates being missing (lacking).
The missing substrate in the batch of substrates may invite troubles in the succeeding processes to be performed in the substrate processing part.
At the cleaning step or the drying step, for example, a plurality of substrates forming a batch are placed in a cleaning bath or drying bath so as to clean or dry the substrates at the same time. However, since the missing substrate in the batch of substrates leads to nonuniform distances between the adjacent substrates, a cleaning liquid or drying vapor contacts the substrates at different rates. In this case, a uniform cleaning effect or drying effect may not be provided.
Particularly at the substrate cleaning step, the batch of substrates is immersed in a cleaning liquid contained in a cleaning bath, under conditions where front surfaces (surface on which a circuit is formed) of the adjacent substrates are opposed to each other while rear surfaces of the adjacent substrates are opposed to each other, in order that contaminants peeled from the rear surface of one substrate are prevented from adhering again to the front surface of the adjacent substrate. However, when the batch of substrates lacks one or more substrates, it occurs that the front surface of the substrate faces the rear surface of the adjacent substrate, so that contaminants of the rear surface may undesirably adhere again to the front surface at the substrate cleaning step.
The present invention has been made in view of the foregoing respect. The object of the present invention is to provide a batch forming apparatus, a substrate processing system, a batch forming method, and a storage medium, that are capable of, even when a plurality of substrates contained in respective carriers fail to successively be aligned in a row with one or more substrates being missing, replacing the missing substrate by changing positional relationships of the substrates relative to each other. According to the present invention, the batch can be prevented from lacking one or more substrates, whereby possible troubles resulting from the missing substrate in the batch can be prevented from occurring in the following batch processes.